Most conventional polymer materials consist of polymers having a main chain formed of C--C covalent bonds. These materials are superior in mechanical properties such as processability, moldability or flexibility. Further, the materials are so electrically insulating that they are used as an insulating material for many electrically components.
Polymers having a main chain of siloxane bonds instead of C--C covalent bonds, called silicone resin, are also in use as electrically insulating materials.
Aluminum oxide dielectric films for aluminum electrolytic capacitors or the like are self-recovering. Specifically, an aluminum film on the surface of aluminum electrodes is passive, and the film forms a dense oxide film. A pin hole or defect on the aluminum oxide dielectric films is anodized by the electric field in the electrolytic solution. The aluminum oxide dielectric film is thus recovered.
However, no insulating polymers capable of recovering insulation on their own were found. Polymers in wide use as insulating materials usually consist of polymers having a main chain of C--C covalent bonds. Such polymers, however, had many problems. For example, the degree of polymerization decreases due to decomposition of the polymer by high electric-field or high temperatures. In the contrary case, double bonds (C.dbd.C) are often formed so that the polymer is gradually carbonized. A conductive tree phenomenon or a tracking phenomenon then takes place, finally causing dielectric breakdown. The arc generating from a void or crack carbonizes the polymer, similarly causing dielectric breakdown. The smaller the device, the more serious was the problem of deteriorating the insulating properties. For that reason, polymer materials which exhibit a high breakdown voltage and a high durability in microelements have been desired.